For the following questions answer them individually
0.25 g of an organic compound "A" containing carbon, hydrogen and oxygen was analysed using the combustion method. There was an increase in mass of $$CaCl_{2}$$ tube and potash tube at the end of the experiment. The amount was found to be 0.15 g and 0.1837 g, respectively. The percentage of oxygen in compound A is __ %. (Nearest integer)
(Given: molar massing $$mol^{-1}$$ H : 1, C : 12, O : 16)
Molar conductivity of a weak acid HQ of concentration 0.18 M was found to be 1/30 of the molar conductivity of another weak acid HZ with concentration of 0.02M. If $$\lambda^{\circ}{}_{Q}-$$ happened to be equal with $$\lambda^{\circ}{}_{Z}-$$, then the difference of the $$pK_{a}$$ values of the two weak acids $$(pK_{a}(HQ) - pK_{a}(HZ))$$ is ___ (Nearest integer).
[Given: degree of dissociation ($$\alpha$$) << 1 for both weak acids, $$\lambda^{\circ}$$ : limiting molar conductivity of ions]
A chromium complex with a formula $$CrCl_{3}.6H_{2}O$$ has a spin only magnetic moment value of 3.87 BM and its solution conductivity corresponds to 1:2 electrolyte. 2.75 g of the complex solution was initially passed through a cation exchanger. The solution obtained after the process was reacted with excess of $$AgNO_{3}$$. The amount of AgCI formed in the above process is __ g. (Nearest
integer)
[Given: Molar massing $$mol^{-1}$$ Cr:52; Cl:35.5, Ag:108, 0:16, H:1]
Grignard reagent RMgBr (P) reacts with water and forms a gas (Q). One gram of Q occupies $$1.4 dm^{3}$$ at STP.(P) on reaction with dry ice in dry ether followed by $$H_{3}O^{+}$$ fonns a compound (Z). 0.1 mole of(Z) will weigh ____ g. (Nearest integer)
The half-life of $${}^{65}Zn$$ is 245 days. After x days, 75% of original activity remained. The value of x in days is ___ . (Nearest integer)
(Given: log 3 = 0.4771 and log 2 = 0.3010)
